Spraying apparatus



Dec. 14, 1937. L. sToEsLlNG SPRAYING APPARATUS Filed Feb. 19, 1935 2Sheets-Sheet l I/v VEN TOR L U0 w/G STOESL//VG A rroR/vy.

Dec. 14, 1937. g STOESUNG 2,101,922

SPRAYING APPARgTU Filed Feb. 19, 1935 2 sheets-sheet 2 Y [NVE/v70@LuDw/G SToEL//VG A TToR/VEY.

ZNE RECEIVING JUD/V/DED MATER/AL Patented Dec. 14,- 1937 UNITED STATESPATENT OFFICE sPnAnNG APPARATUS Ludwig Stoesling, Monrovia, Calif.Application February 19, 19a-esami No. 7,237

21 Claims.

- My invention relates to devices and methods for applying coatingsordeposits on a surface, and more particularly to a novel method andapparatus for spraying various materials onto such a surface forprotecting or other purposes vsuch as for water-proofing, acid-proong,alkali-proofing, etc.v

For purpose of definiteness and illustration the invention will beparticularly described in co'njunction with a novel water-proofingprocess which also produces an acid-proof and alkaliproof, though itshould be understood that various materials can be applied and thatvarious functions can be-y performed by the applied coating materials. v

Various processes of. applying water-proong coatings are known to theart, but all are subject to many objections as to mode of application,effectiveness, or cost. Thus, it has been proposed to apply parailincoatings to porous surfaces such as concrete, brick, rock, etc. byapplication of paraiiin in melted condition by means of a brush. Thisprocess is not only objectionable in its mode of application but testshave demonstrated that the paraiiin does not penetrate to the desireddepth to be completely effective in the -absence 'of auxiliary stepsperformed only at prohibitive cost. So also, 'one of the-most widelyused processes applies paraiiln while dissolved in a solvent,evaporation of this solvent leaving a deposit of paraffin. This processis unsatisfactory `for many existing conditions in that the resultantdeposit is of a spongelike character and will not completely prevent thepassage therethrough of -water or other liquids.

Generally speaking, the invention has two aspects, especially withregard to the problem of spraying materials such as parafiln. These twofactors or aspects involved can best be explained and illustrated inconjunction with a parainspraying system, and for this reason theinvention will be particularly described with reference thereto, thoughit will be clear that somewhat similar factors are present in thespraying of Avarious materials. In the ilrst place'. spraying anymaterial such as parailin has beenyheretoiore impractical due to thefact that the atomized parafn solidies to form a snow as soon as it isdischarged rom the spraying device, thus preventing any material amountof penetration. In the present invention the atomized stream of parafnor other material is protected from contact with the atmosphere as itmoves toward the surface on which the deposit is to be formed. In thesecond place, the problem as to how to secure greater penetration of thecoating material has been a serious and unsolved one. In the presentinvention greater penetration of the material is obtained'by the properapplication of heat, the spraying devices herein illustrated eiecting anovel pre-heating and post-heating of a particular zone in the surface,as will be hereinafter described.

It is an object of the present invention to provide a-novel method ofspraying a material onto a suriaceand which has superior penetrating andpressure-withstanding powers, and which produces a coating which hassuperior protecting properties.

It is a further object of the invention to spray a liquid or powderedmaterial onto a surface in such a manner that the material is protectedfrom contact with the atmosphere during its travel from the sprayingdevice to the surface.

Another object of the invention is to provide fa novel spraying methodin which the spray of subdivided material is surrounded by a moving'stream of gas as it is projected toward the suriace to be coated.

It is another object of the present invention to provide a novel methodof spraying which is very satisfactory for use with materials whichsolidify upon cooling, such as parann, the material being atomized whilein melted state and being prevented from cooling while in this atomizedstate by heat applied to the atomized material before it reaches thesurface,l or by surrounding the atomized material with an envelope ofgas preventing direct heat transfer between the atomized material andthe atmosphere.

A further object of the present invention is to provide a novel methodof pre-heating and postheating a zone of the surface to increase thepenetration or otherwise increase the effectiveness or integrity oi thecoating.

It is another object of the' present invention to provide a novellow-pressure method of spraying applicable to various uses and verysatisfactory for spraying various materials.

The' apparatus for supplying such a coating, constructed as shown orsuggested herein, is also believed to be novel, and it is an object ofthe present invention to provide a novel concentricstream sprayingdevice for sprayingY various materials in subdivided form. y

It is a further object of the present invention to provide a novelspraying device having a novel l relationship between a heating meansand the other elements of the device and also a device in which theheating means is of novel construction.

It is a-further object of the linvention to provide a heat-responsivestructurein such a spraying device for indicating or controlling thetemperature developed.

A further object of the invention lies in the provision of a sprayingdevice with a main passage in which is positioned a tube, a stream oi'vgas being moved ,through this tube and another stream of gas being movedthrough anv annular space betweenthe tube and the walls of the mainPassage- It is a further object of the invention to provide an outerVenturi tube in conjunction with a tube therein, or sometimes inconjunction with a structure in which this tube is in` the form of aninner Venturi tube, this 'double-venturiy having -beenfound to be veryeffective in producing the concentric streams.

Another object of the invention lies in thel provision of a novellow-pressure spraying device. and is very satisfactory in sprayingmaterials which solidify when exposed to the atmosphere. K

Further objects and advantages of the invention will be made'evident tothose skilled in the art from the following description of severalembodiments of the invention. i

Referring to the drawings:

Fig. l is a vertical sectional view of one em-' ffalls within theobjects enumerated above: The

spraying device therein shown is of the manual'- ly-supported orportable type and includes a body structure Il. 'I'his body structuremay be formed of a singlemember, but is preferably formed of acylindrical shell il with a plate i2' 'extending across the forward endthereof and detachably connected thereto as by screws Il,

this body structure forming a chamber i4 inside the shell il.

Extending rearwardly in the chamber il are inner and outer tubularmembers il and i1 suitably secured at their forward ends lto the bodystructure Il. In the embodiment shown. the inner tubular member i. ispressed into an opening of the plate I2, while the outer tubular memberI1 is pressed into an opening of the shell. Il.

These tubular members 'are spaced from Veach other to define an' annularspace il into which a heating unit 2l extends.

This heating unit 2l may take any one of a various number of forms. Inthe embodiment illustrated it includes a rear head`2| and a for`ward-extending sleeve 22 formed integrally or separately of a suitableheat-resistant material such as baked fireclay, the material which Iprefer using being fA1undum". The rear head 2| may be vused to whollyorpartially Aclose the rear end of the chamber Il, beingfshown as belnsing connected to the shell Il by screws/22 which extend through aprotecting ring 2l and through a picking of asbestos or lother material2B sep arating this ring from the rear head 2l.

'I'he sleeve 22 divides the annular space' i! between the inner andouter tubular members It and I1 into inner and intermediate annularpassages 21 and 28; 'I'he forward end of the' sleeve 22 terminates shortof the plate i2 so as to .throw the forward ends of these annularpassagesl into communication, thereby providing a tortuous passagethrough which 'a stream of gas may be moved, as will be hereinafterdescribed. y

A -suitable heating means 2! is supported by the sleeve 22 and is shownas comprising a coil of resistance wire wound helically around` thesleeve 22. Ihe several turns of this helicallydisposed winding arepermanently spaced from each other by winding the coil in a helicalgroove 3U which is preferably of greater radius of curvature than \theycoil itself. -With such a construction it is possible to obtain amaximum heating of the gas moving through the intermediate passage 28for the gas comes into contact with substantially all portions of theresistance wire, the only portion not contacted by the gas being thesmallyportion thereof engaging the bottom of the helical groove 30. Thisgas is also heated vby contact with the heated sleeve-'22 as it flowstherealong. Y

'I'he requisite current may be supplied to the heating unit 20 throughconductors 3i and 22 connected to suitable terminals of a socketretained in the rear head 2|. A plug 28 provides correspondingly placedterminals supplied with current through two conductors oi a cable 31.these .conductors being indicated by' the numerals 3l and '39.

A stream of gas is supplied tothe spraying device preferably through ahandle Il which may be formed of a. length of pipe, the. cable 81extending therealong and being held in place by a cord or other memberwound therearound. In many instances this gas can be air supplied to thehandle ll through a hose 42 detachably connected thereto, fa suitablepumping means 43 being utilized, this pumping means being illustrated asa conventional low-pressure blower. The air moving upward in the handle4U isv discharged into an annularspace 45 between the shell il and theouter tubular member I1, flowing peripherally around this tubular memberand toward th'e rear end thereof as indicated by the arrows I8. Thisstream of gas then moves lthrough the intermediate annular spaceA 28 as.indicated by the arrows I1, being therein heated by the coll ofresistance wire and by contact with the heated sleeve 22. 'Ihis aircontinues its movement through the` tortuous passage by movlng throughthe inner annular space 21 as indicated by the arrows 48. beingadditionally heated therein by contact with the sleeve 22 and being thenguided so as to move as a main stream through the inner tubular memberit, as indicated by the arrows 49. If desired, this main stream may begiven a rotary movement as it moves through the inner tubular menber I6by riding the passage "defined thereby or by po' vidinghelically-disposed vane means '5| therein.

' However, it should be clear that it is not essential to theoperativeness of the device that such a rotary movement be imparted tothe main stream of gas, though this auxiliary factor is desirableincertain instances.

While separate sources maybe utilized for supplying the concentricstreams of atomized material and gas moving toward the surface to becoated, I prefer to divide the main stream of gas moving through thepassage 58 into inner and outer streams, the inner stream being utilizedto carry the subdivided material to the surface. In the embodiment shownin Fig. 1 this is accomplished by the use of a head structure Ell shownas comprising a head 6I detachably connected to the plate I2 andcarrying a nozzle 62 extending forwardfrom this head. The head structure60 provides an opening 84 forming a part of the main passage and which,in the embodiment shownv in Fig. 1, is in the form of an outer Venturiproviding a throat 85 which is somewhat smaller in diameter than therearward and forward flared portions-66 and 81 thereof. A tube88'iscentrally disposed in the opening 64, being preferably secured tothe head 8| as by an arm 69.'. Ihis tube 68 is'of smaller diameter thanthe opening 64, the forward end vthereof bounding an inner orifice means10, this sleeve cooperating with the opening 64 in defining an outerorifice means 1I of'annular shape.

Means is provided for `supplying to the innerA orifice means 10 thesubdivided material. In the embodiment shown in Fig. l this isaccomplished by forming the tube 68 as an inner venturi, the atomizedmaterial being discharged therefrom in or near the throat 85 of theouter venturi'. This inner venturi is shown as providing apas- 'sageincluding a throat 13 and forward and rear;

Ward diverging portions 14 and 15. The rear end thereof is relativelysharp so as to divide the main stream of gas into two streams, oneflowing through the passage of the inner venturi, and the other flowingthrough the annular space between the tube 68 andthe walls of theopening il. i

The material to be atomized or subdivided isA moved into the tube 88preferably at a position adjacent the throat 13. A suitable passagemeans is utilized in this regard, being shown as including a verticalpassage 11 extending throughvthe arm S9 and communicating with ahorizontal' passage 18, the flow of material through these passagesbeing controlled by the setting of a valve 19 shown in open position. Ahandle 8D serves to permit manual movement of this valve, the

valve being closed when this handle is in its dotted-line position. n

While any suitable conduit means may be utilized to supply the materialto the passages 18 and `11, the preferred embodiment of the inventionincludes a receptacle 8| vfor this material and, positioned inheat-transferring relation with the same heating unit 20 as is utilizedfor heating the gas. As best shown in Fig. 2 this receptacle is securedto Afianges-82 extending sidewise from the shell I I and cooperates withthe upper periphery `of this shell in defining a chamber 83, the lowerportions of which are below the uppermost part of this shell, extendingdownward therearound. The material therein receives heat through theshell II. Thus, in spraying paraffin the paraffin can be introduced intothe chamber 83 in solid state, being therein melted.

The material flows from the lowermost portions of the chamber 83through` one.or more passages 84 extending through the shell II and theplate I2 and opening 'on an annular chamber or groove 85 formed in theforward face of the plate I2, this groove bein'g in communication at itsupperV end with the horizontal passage 18. The material thus flows bygravity from 'the receptacle 80 to the throat of the inner venturi.

, In addition, Athe 'reduced-pressure in the throat of thel innerventuri (due to rthe increased vestate untill they reach the surface 88.

locity of the gas flowing therethrough) acts to forcibly withdraw thematerial from 'the receptacle 8l). In this connection it is possiblewith the lstructure shown to completely drain the chamber 83, a verydesirable factor.

If desired, a nipple 81 may be positioned in the passage ,11 to extend adistance into the throat of the inner venturi, the lower end beingangled as shown. However, the use of such a nipple is usually notnecessary, the' device being entirely satisfactory if the material flowsdirectly from lthe passage 11 into the throat 13. Regardless of whetheror not the nipple 81 is utilized, it will be clear that the materialmoving through the passage 11 is picked up by the stream of gas movingthrough the inner venturi and is subdivided or atomized, the atomizedmaterial being delivered by the forward-diverging passage 14 to theinner orifice means 10. In the embodiment illustrated this atomizedmaterial is discharged toward a I changes in the material being sprayedor to hold the spray more intact.

If paraiiin is being sprayed,\it is essential that the liquid paraffinparticles in this spray be maintained in liquid particles are allowed tocool, either by contact with a cool atmosphere or by excessive expansionof the gases discharged from the inner orifice means 10, solidiiicationthereof will take place and it will be impossible to spray the paraffinin liquid state onto the surface 88. Such solidiflcation canbe avoidedby applying heat to the atomized material after it is discharged fromthe spraying device, or by separating the atomized Amaterial from theatmosphere by a heatinsu lating stream of gas which is usually itselfheated, or by both of these expedients. In the embodiment shown in Fig.l, both expedients are uti lized, though it will be clear that theseexpedients can be separately utilized. In this connection it will benoted that the annular orifice means 1I discharges an annular stream ofgas which is con- If these centric with the stream of atomized material,

the outer boundaries of this stream of gas `being indicated by thedotted lines of Fig. l. This stream of gas tends to heat-insulate thestream of atomized material from the surrounding atmosphere. Further, inthe embodiment' shown in Fig. 1 this annular stream of gas is heated,thus further tending to prevent cooling of the atomized' material. It issometimes preferable to maintain this stream'of gas at a temperaturesomewhat above the temperature of 'theatomized material, thus actuallyheating the atomized ma'- terial further during *its passage from thespraying device to the surface 88. In' this connection it will be clearthat while the temperature of the f.

gas entering the inner venturi is the same as the gas moving through theannular space between the tube |58- and thewallsof the opening 64, vtheatomized material moving from the inner orifice means 10 is somewhatcooler due to the addition of the somewhat cooler material to beatomized and due to any expansion which takes placein theforward-diverging passage 14. Thus, the temperature of the annularstream of gas discharged from the outer orifice means 1I is considerablyhigher, and by proper design the ternperature of the surrounding conicalstream of air the forwardfdiverging passage 'M is an important i one.l Ihave found that in spraying such materials it is impossible to securegoodi'results it lv thepressure of the pump means 43 is too high.Heretofore all .spraying processes with which I am familiar haveutilized pressures of from to 100 lbs./sq. in. or more. While suchpressures can be sometimes utilized in my spraying device y 1,5 inspraying certain materials, these pressures are entirely ineectual toproduce best results when spraying other materials such as paramn, or

other materials which solidify uponpexposure to .they atmosphere. Withsuch materials I have 20 found it desirable to utilize much`lowerpressures, using, in fact, as low a pressure as pos/sible and stillsecure the desired atomiz'ing'action. With such materials best resultsare secured if the pressure in the main passage -'doe`s not exceed a fewpounds per square inch, with one or two exceptions pressures of not toexceed three pounds per square inch have been entirely satisfactory. Inspraying paramnand certain other `materials I prefer to utilize as low apressure as possible, the pressure being'only sufficient to insure thatthe atomized material will move to the surface to be y coated. Entirelysatisfactory results have been obtained by utilizing pressures of twelveinches of water or less. One factor in this connection is', of

course, the direction of movement of the sprayed material. If thesprayisdirected'vertically upward, it is usually necessary to use pressuresoi' l between eight and twelve inches o f water. When the spray isdirected -horizontally or vertically 40 downward, pressures as low asfour l water are very satisfactory. 1

There are several reasons for my utilization of low pressures inthe'p'referred embodiments of my invention. In the, first place,- it isvery desirable that the atomized particles be not impinged upon thesurface 98 at such high velocity that they will rebound therefrom. Thisfactor is especially importantif the atomized lstream is in 'the form ofa cone, for if the velocity of the atom- 5'@ ized particles is too nighthese particles wiu rebound from the surface B8 outward towardthe Isurrounding stream of gas and sometimes therethrough so as tocontaminate the surrounding at mosphere or be prematurely deposited insolid gform on surfaces which are to be later coated.

In the second place, it is important to maintain the atomized parainparticles in liquid state during passage from-the spraying device to'the- .surface 88,.v In this connection it is importantto Icooling theatonized particles.

o0 prevent cooling of 'these' atomized'particles to any great degree. Ifhigh-pressure gas is utilized for` formation of the spray of atomizedmaterial, this gas excessively expands upon being discharged from theinner.A orice means, thus 'necessarily As an example of this, -I havefound that `if the temperature of the atomized stream of paraflin is600, F. at the forward end-of the nozzle l2, the temperature onehalfinch in front of this positionwill be 590 In'the spraying of parain orcertain other may agendas I utilizing high pressures, the temperature ofthe atomized materiali as it leaves the' spraying device' m-ay b'e 300vF., vdropping, to .i 300 F. by the time that the atomized materialreaches` the surface, a drop in temperature of 400 F. This excessivedrop in temperatureis caused primarily by the greater expansion of `thegas in the atomizedv spray, but isinuenccd also by the higher velocityof the outerV stream of gaswhich tends to suck in a portion of thesurrounding atmosphere, thereby cooling. this stream of gas. y

. In the third place, higher pressures result in higher velocities ofthe concentric streams. As to the surrounding stream `of gas,v suchhigher velocities are detrimental in that excessive turbulence is set upwhen this stream contacts the surface 8d. If lower velocities areutilized, this surrounding stream will fiare outward adjacent thesurface 88, creeping therealong rather than rebounding therefrom or'creating excessive turbulence. 'This creeping action of the outer streamof gas is indicated'by the dotted lines 90 of Fig. l. Such aslower-moving stream'of surrounding gas also oiers greater resistance tospreading of the atomized stream when it contacts the surface 88. In thefourth place, it is desirable that this surrounding stream of gastransmit to the surface 8S as many of the heat units per unitof'time asy to use a relatively large quantity of heated gas mitting to thesurface 88\the desired quantity of heat units. This expedient-alsoavoids the ex'- at higher velocity and thus incapable of trans--cessive lover-heating `of the .gas resulting if a high velocity streamis Aused and if Vthetem'pera- 1 will often dtrimentally aifect thematerial to be sprayed, many of these materials losing theireffectiveness if heated to too great a degree preparatory to applicationto a surface.

I 'usually find it desirable to provide on or adjacent the sprayingdevice a heat-responsive means'e'ither in the form of 'a simplethermometer or in the form of a thermostatso connected as to lregulatethe temperature'of Vthe gas. In the embodiment shownin Fig. 1, `Iposition such a Aheat-responsive means-in the path of flow of the l gasas it moves from, the intermediate passage 2i!v to the passage 50, beingthus responsive to. the final temperature of the gasdelivered to thismain passage. A sshown, this heat-responsive means includes a coil ofbi-/metallic material 95 secured at on'e end throughv ai pin 96 to adial 91 offa heat-indicating means 98.' This means is suitably encasedin a shell 99 lclosed by a glass |00, the` 'shell 99 being retained in acavity of the rear head .2i infthe -preferredembodiment of theinvention. The other end of the bi^metallic strip :4 is securedv to apin -lill which Vciairries a hand or. pointer |02 moving across suitablegraduati'ons on the dial l1. Such a heat-responsive means will indicateto the operator the temperature'of the gas entering the main passagev50.

` In addition, it issometimes desirable to utilize the heat-responsivemeans 88 as a thermostat to regulate the temperature of this stream ofgas. In the embodiment shown this is accomplished by extending the hand|02 below the pin |0| to form a movable contact |04, which engages astationary spring contact |05 when the temperature increases to orexceeds the desired degree, remaining out of Contact therewith attemperatures between atmospheric t-emperature and the desiredtemperature to be maintained. These contacts are respectively connectedto conductors |06 and |01 extending to corresponding terminals of thesocket 35 and forming a part of a control circuit,

.. the plug 36 containing correspondingly positioned Y from theconductor terminals connected to conductors |08 and |09 of the cable 31,the latter conductors terminating in an auxiliary plug ||0. Acorresponding auxiliary socket lli indicated by dozted lines continuesthe control circuit to include the secondary winding l|2 of a step-downtransformer H3, the primary winding of this transformer being connectedacross conductors ||4 and ||5 connected to a conventional plug H6. Alsoincluded in the control circuit in series with the secondary |2 is awinding of a relay ||1, this winding being indicated by thenumeral H8.

The conductors 39 and 38 carrying the main current to the heating unit20 terminate in a main plug |20 adapted to fit in a main socket |2| fromwhich extend conductors |22 and |23 corresponding to-the conductors 39and 38. The conductor |22 is connected to the conductor ||4. Theconductor |23 is connected to a contact |25 of the relay ||1 through animpedance shown as comprising a resistor |21, and is also directlyconnected to a contact |26 of this relay. A movable contact member |30of the relay ||1 is normally retained in engagement with the contact |26as by a spring |31. However, energization of the winding i8 of thisrelay moves this contact member |30 into engagement with the contact|25. A conductor |33 connects the, contact member |30 to the conductor I|5.

Assuming that the temperature is below the desired degree, the winding||8 will not be energzed, and the contact member |30 will engage thecontact |26. At this time current will now ||5 through the contactmember |30, thence through the contact |25, the conductors |23, 38, and3| to the heating unit 20. returning through the conductors 32, 39, and|22 to the conductor I4, thus energizing the heating unit to a maximumdegree.

As soon as the temperature reaches or exceeds the desired value, thecontacts |04 and |05 close,

thus completing the control circuit. At this time current ilows throughthis control circuit from the lower terminal of the secondary I2, andsuccessively through the relay winding ||8, conductors |09 and |01, andthence through the contacts |05 and |04, yreturning to the secondarywinding ||2 through conductors |06 and |08. This willenergize thewinding ||8 to move the contact' member |30 into engagement with thecontact |25. The effect of this change in position of the contact member|30 is to somewhat decrease the current flowing through the heating unitdue to the fact that the resistance |21 is now in the main heatingcircuit. While it is sometimes. possible to completely cut off thevheating current when the temperature has` reached the desired degree,it is usually preferable to merely decrease this current to a valuelnsumcient to maintain the desired temperature. Such a syslbe from alfto 1/2".

tem requires operation of the relay ||1 at less frequent intervals.

It will, of course, be understood that the thermostatic system disclosedisl only one of a number of control'systems which can be utilized forcontrolling the temperature of the gas moving through the main passageA50. Furthermore, if it is not desired to automaticallycontrol thetempcrature, the control circuit can be rendered inoperative by merelydisconnecting the auxiliary plug ||0 and the auxiliary socket Variousmeans may be' utilized for driving the 'pumping means 43. In thepreferred vembodiment, I utilize an electric motor |40 in this capacity,connecting this motor across the conductors ||4 and H5.

' The superior penetrating yproperties of my method cannot be accountedfor by any high ve- 4 locity of the atomized particles, for when lowpressures are used the impact of these atomized particles is notsufficient to force these particles any material distance into thesurface. However. my process has been definitely shown to produce adeeper-penetrating coating than existing processes. Thus, for instance,in spraying paraln on brick I have been able to secure penetrations ofapproximately two inches. In spraying ordinary concrete the penetrationby use of my process will With blown concrete this penetration will beeven greater. Thus with my process it is possible to obtain penetrationsfar greater than with other processes, these greater penetrations beingmore than double or triple the penetration possible, for instance, bythe use of a paraffin-coating process in which a single application ofthe paraffin is applied with a brush orv tration available makespossible the formation of an impervious coating which will allow nowater whatsoever to movetherethrough over an indelinitelength of time.In this connection I have found my method of -coating to be veryeffective in retaining moisture in a body of concrete by applying to theexposed surfaces of the concrete,

shortly after the forms have been removed, a

penetrating coating of paraiiin or similar material. After this is doneI have found that the concrete contracts materially less than would bethe case if the surfaces thereof were allowed lto remain in contactwlththe atmosphere. Furthermore, I have found that the contraction insuch instance when utilizing my process is only one-fifth of the linearcontraction which takes place if the lbest coating process nowcommercially available is utilized. I have furthermore found that bythus coating the surfaces of concrete after the forms have been removedthe compression strength of the concrete is increased from 14% to 18%,and that the minute aircracks ordinarily formed if the concrete isallowed to vremain exposed to the atmosphere are entirely eliminated.These vnew results aredue to the 'lo Vconcrete.

met 'that my process is particularly effective' in preventing escape ofany of the moisture which still remains rin the concrete, allowing all-of this moisture to be equally distributed throughout the crossesectionof the concrete, andperess produces a penetrating coating capable of.

withstanding high pressures. Thus, if para is sprayed onto concrete bymyfprocess, uti

l5 only small quantities of par'ifrom V3 to 1/2 oz. per square foot) theresulting coating `will withstand, pressures exerted on the face of thecoating of 360 pounds perisquare inch or more.

Furthermore, ,if pressure is applied to the rear.-

2o ofthe concrete, thus tending to force the parain frizoni the coatedsurface, the coatingv applied by my process will withstand ures inexcess ctl00 `pounds per square inch /without leakage or removal fromthe surface. i

One factor insecuring this incre penetration is the fact that the paralnparticles are all maintained in liquidstate until they reach the"surface,v as distinct from other processes oi?v applying hot par inwhich a portion of the par may prematurelysolidify when applied with abrush or other applying means. Fundamentally, however, thedeeperpenetration cfected by -my -process is caused by a novelpref heating andpost-heating eiected by the enveloplng hot stream of gas and can best beunderauftransverse..lines i435 to its, and the arrows adjacent thissinuous line, indicate the path of f movement of the central axis ofthespray of. atomized material as the spraying deviceis ved to and froin advancing relationship across the surface idd,- I have indicatediafgiveninstantaneous position of this axis by` the numeral 852. When inthis given position the atomized stream will cover an area inside acircle H53, while the lstream' of heated gas will impinge agt theSurface lin a surrounding area dened between the circles i553 and |54. tConsidering .the action which takes place in a zone B5B as the sprayingdevice' is moved to the right along the dotted line ille, vit will beclearvv thatthls zone will be first pre-heated by contact with the upperquadrant of the stream of heated gas. When the spray issubsequentlymoved leftward axially along the dotted line ist, this zone will beadditionally pre-heated by the side quad- 60 rant of the annular streamof gas.' Further left-U wardmovementalong the line |41 will bring thezone |56 inthe atomized spray, so that-after two vpre-heating steps theparaiiln, for instance, is .ap-

plied to the zone E56, without permitting any I g.; cooling between thesecond pre-heating step and the application of parafn., As thespray is'moved'. lftward a'-further distance along the dotted line I", the vzone|55 will be post-heated by the other sidedqusdrant or the strem of gas.

.i 7 0 $0 also, whemata later period of time, the spray Vis being movedrightward along the dotted line i 75 vthegases near the surface of the,f` In this embodiment of the invenntion' the arci-,92s.-

stp prevents such solldiication. By post-heat- 10 ingithe zone G56, theparan is maintained in liquid iorm and is forced deeper intothe' pores.As soon as the post-heating has been completed. the heated air in thepores rapidly cools by heat conduction.

deeper-embeddedmortions of the concrete, and

secondarily heat nows to the surrounding atmosphere. The result is thatthe cooling air con- 1 tracts before the parain vhas solidied, thiscontraction drawing the param into the pores 20 andthus eecting a muchdeeper penetration 1 .than hasher'etofore been obtainable. Successivepost-heating is desirable in that it tends to further increase thisdepth oi penetration;

While the temperature of the gas enteringk the 25 main :at can vary overwide :firm-with most materials, I have found it de utilize rather hightemperatures in the spraying of materials such-.as paramn. I prefer toutilise a very high-grade parain such, for instance, as 30 f. Borneoparamn, utilizing temperatures of from 550" F. to 660 F., thetemperature oftild" F. being found very satisfactory in spraying paramn.However, no xed temperature can be set forth 'for all materials. Thus,in spraying asphalt 35 it is possible to utilizesomewhat lower tempera-`tures, while in spraying sulphur-silica tempera.- tures between 250 F.and 280 F. may be utilized. though best results are obtained withwfas-'s tures from 265 Kit-to 275 F. In sprayingfthe 40 more criticalmateriala such as sulphur-silica,

'it is very desirable to use a' thermostatio means.

Regardless of the material being sprayed, the temperatures utilizedshould not exceed the flashpoint of such material. c Alternativespraying devices capable ci' forming the concentric streams aredisclosed in Figs. 3,'4, and 5.- Reierrlng particularly .to Fig. 3, Ihave illustrated'amodied form ojhead struc. ture detachably connected tothe-plate i2 in 50 place of the head Si. This embodiment utilizes atubular construction including a head member A12Enl spaced from aforward member 2M by an outer sleeve' 2M, an inner sleeve 2W alsoextending between these members and cooperating with v/55 the outersleeve 202 and denning an annular space 2M. ,The main stream of gas isconducted from the inner tubular member i5 to the inner sleeve 203 sothat the main passage in this form of the invention is formed by both ofthese ele-j ftill ments-this main passage being indicated by the'numeral 2U5. v

' Positioned in this mainpassage is a tube 206 shown as being in theformof an inner venturi similar to the structure .shown in Fig. land be-J y the hakt oWS t0 the 15- teriai to be sprayed is introduced through apassage means 2|5 of the head member 20, the flow being controlled by avalve 2|6. The passage means 2|5 communicates with a pipe means 2|`|disposed in heat-transferring relationship with theggas movingl throughthe main passage 205. A preferable mode of effecting this result is toform the pipe means 2|'| in the form of a helix extended in the annularspace 204. The forward end of this pipe means communicates with thethroat of the inner orifice means through a suitable valve 2|8. Thisvalve may be used alternativelywith the valve 2|6. Usually, however, itis sufficient if the valve 2|8 acts as a regulating .f means to controlthe maximum flow of the material introduced into the inner venturi.Material may be supplied to thepassage means 2|5 from the receptacle 80in which event a dual heating of the material will be effected, thematerial being preliminarily heated in the receptacle and being furtherheated in the pipe means 2|`|. In other instances, the passage means2|'5 can communicate with a pipe or hose 220 acting .member 23D with asleeve 23| extending forward therefrom and cooperating in forming themain gas passage, A forward member 232 provides a cavity into which thissleeve extends and provides an opening 233 which converges forf wardly.In this embodiment the tube, such as the tubef68 or206 previouslydescribed, it is not in the form of a venturi but comprises a relativelylong tube 235 bounding an inner orifice" means 236 at its forward endand cooperating with the opening 233 in defining an outer orifice means231 of annular shape. This tube 235 is closed atits .rear end by anysuitable means, such as a central-member 238, which may serve to supportthis tube, being in turn supported by an arm 239 of the head member 230The passage means delivering the material includes in ythis embodimentan inner tube 24| carried by 'the central member 238 and extendingforward in the tube 235 to a position beyond one or more openings 242formed in the tube 235.

In this embodiment the main stream of gas is divided into two streams,one being an annular stream and being discharged through the outer oricemeans 231, and the other being a stream formed inside the pipe 235 whena portion of the gas moves through the openings 242 and forward throughthe annular space between the tubes 235 and 24|. The latter stream ofgas forcibly withdraws the material from the inner pipe 24| and thusfrom the passage means, acting to atomize this material as soon as it isdischarged from this innerl tube. In this embodiment I have not found itnecessary to utlize venturis for purposes of atomization or forproducing the concentric streams.

In Fig. 5 is shown a modified hed structure including a head member 250secured to the plate |2 and providing a nozzle 25| which may be formedintegrally therewith. This nozzle provides an opening 252 whichispreferably, though not necessarily, of Venturi shape. The centralaior'foaaf,

member 238 and its supporting ar'm 239 are substantially the same asindicatedin Fig. 4, sup porting the tube 235 and the in ner tube 24|.However, the openings 242 in this embodiment are positioned in theintake passage of the venturi so that a portion of the main stream of.

gas moves through these openings into the annular space between'thetubes 235 and 24|. The remaining gas from this main stream is dischargedthrough an outer orifice means 255 between the tube 235 and the walls ofthe opening 252. Preferably -both ofthe tubes 235 and 24| terminate nearthe throat of the venturi, very satisfactory results having beenobtained by extending the inner tube 24| a slight distance beyond theforward end of the tube 235. The atomizing action is such that an innerstream of subdivided material is projected', being enveloped by a movingstream of hot gas as previously described, atomization taking place atthe forward ends of the tubes 235 and 24|. The action of thisconstruction can sometimes be improved by using helically disposed vanemeans 260 in the main passage. j

The head structures shown in Figs. 4 and 5 can be used for variousmaterials, including the materials previously suggested. They areparticularly adapted for spraying such materials as sulphur-silica.

The spraying devices herein described Ican be used at various spacingsfrom the surface to be coated. On the smaller units herein describedthis distance is usually less than 6 inches, though larger spacings canbe used. This spacing depends in part upon the temperature of thesurrounding atmosphere andthe Surface to be coated. Usually on hot daysor when the surface is already warm the larger spacings can be usedto'best advantage, while on cooler days or when the surface is rathercool the smaller spacings are more desirable.

It will be clear that my invention is not limited to the particularembodiments herein disclosed, finding utility in various capacitieswherein it is desirable to coat* a surface for waterproong,-protecting,or other purposes. While I have particularly described the spraying ofliquids by' atomization or subdivision thereof, my invention can also beused to spray various other materials in powder or granular form, thesurrounding stream of gas serving to separate the sprayed material fromthe surrounding atmosphere. Nor is it necessary to the utility of myinvention that coatings of'a penetrating nature be always applied. Forinstance, the sulphurpenetrate but will bond ous surfaces.

I claim as 'my invention: 1. In a, spraying device of the characterdevery effectively to variscribed, the combination of t a head structurepro- .viding an opening therein; a tube disposed inv said vsilicapreviously mentioned willnot materially' tubular member extendingrearward from said head structure in 'axial alignmentwith said opening'of said head structure; heating means surrounding said'tubular member;means for iiowing a stream of gas through said tubular member, saidstream being heated by said heating means, a portion of said stream ofheated gas iiowing through said tube and another portion of saidheatedgas owingaround said tutaami through said annularoriiice means;and means delivering the material to'be sprayed to said tube wherebysaid material is picked up by said stream of heated gas moving throughsaid tube and is discharged from said inner orifice means, the heatedgas owing through 4said annular orice means being discharged inenveloping relationship with said material.

2. In a spraying device of the class described, the combination of:inner and outer tubular` members spaced from each other to define anannular space; means closing one end of said annula space; annularheating lmeans extending into theother end of said annular space to formsame into a ytortuous passage one end vof which communicates with saidinner tubular member;

, means for deliveringV a stream ofgas through said tortuous passage tobe heated by said annular heatingmeans, said` heated gas' dischargingfrom said` tortuous passage into said inner tubular member; orice means`receiving 'the heated gas from said inner tubular member; and` passagemeans for delivering a material to be sprayed to said heated' gas. i.

. 3.- In a spraying device of the class described, the combination of:'a body structure providing a chamber; a rearward-extending tubularmember attached to said body structure and extending rearward in-saidchamber; an annular heating unit around and spaced fromsaid tubularmember; means for owing a stream of gas betweenl said heating unit andsaid tubular member and thence into said tubular membemian atonizingmeans associated with said body structure and receiving atleast aportion of said heated gas; and means for delivering the material to be'sprayed to said atomizing means.

, d. A combination as defined in claim 3 includ.

heating means'for said air and means delivering a. portion of the heatedair to each of said orifice means; and meansfor. delivering moltenparaiiin to saidinn'er orice means whereby vthe inner stream of air4carries particles of molten parafiin to th surface` to be coated andthe stream.' of

heated air moving through said annular orice lmeans forms a protectingenvelope for said inner stream during its passage to said'surface.

6. A method-'of applying to a surface a coating of-parain, which methodincludes the steps of:``

heating 'said Aparaffin until it is molten; `spraying said paraflin-ontosaid surface inmolten condi-,

, A'tionandkin atomized state by moving toward said es.containingatomizedparain; and protecting said stream of atomized vparamnfrom contact with .4

they atmosphere by surrounding said stream with surface an' inner.stream of low velocity hot air amoving annular envelopeof heated gasowing toward saidsurface in concentric'relation with-- said inner streamof .atomized parailin. i

7.--A method of a. lying to a surface a coat-` f pp contact with` saidsurface inside said annular stream`of gas by means of a stream of hotair -and inheattransferring relationship therewith 75 ing of paraimwhich method Vincludes the steps' of: heating said paraffin until itismolten; atom- 75Y icing said molten paraffin; moving'said atomiaedaromas parain while'dsper'sed inta stream of heated air toward saidsurface from a position spacedtherefrom; and applying heat to saidstream of atomized paramn as it hows through space from said positionspaced from said surface toward said 5 surface to insure that theatomized parajilln will reach and be deposited on said surface in moltencondition. l

8.. A method of applying to a surface 'alcoating of paramn, which methodincludes the steps of; 10 moving a relatively low-velocitystreani ofheated gas through and from a passage towardsaid surface, the impellingpressure in said passage being not in excess of twelve inches of waterto eliminate excessive cooling of said stream of gas such 15 as would becaused by excessive expansion after leaving said-'passage when utilizinghigher Iimpeiling pressures; entraining in said stream of heated gasmolten particles of parain which are carried to said surface 'by saidstream of heated 20 gas, any expansion of said stream of heated gastaking place after discharge from said @passage being minimized by saidlow impelling pressure; and surrounding said stream of Vheated 'gas witha low-velocity concentric stream of hot gas mov- 25 ing concurrentlyandin contact therewith and of' a temperature above the melting point oiparain.

9. A method of applying to'a surface a coating of material, which methodincludes the steps of z' 30' heatinga owing stream of gas;- dividingsaid stream of heatedgas into two concentric inner and outer streamsowing concurrentlyA toward said surface; and introducing into andentraining in said inner streamV particles of the mate- 35 rial to besprayed, which particles are at a temperature slightly below thetemperature of saidv heated gas, whereby said inner stream isfslightlycooled to `allow said outer stream of gas to bey somewhat warmer,thereby supplying heat to. said 40 inner stream of gas during movementtoward said surface. 1

j of heatedgas andthe lmolten particles of paraffin to successive areasVof vsaid surface by moving lsaid stream and said molten particlesrelative to vsaid surface during application of said molten particles tosaid suracaiwhereby agiven area of said surface is rst pre-heated bysaidheated gas on one side of`saidannular stream, then im- 69 mediatelyreceives a deposit of said paramn particlesand is then post-heated by.said locating gas on the other sideV of said annular stream, afterwhich said given area is cooled. by contact with Vthe atmosphere. i.

.,nular stream of non-burning gasheatedto a I temperature above thelmelting temperature of 70 v fparaiin toward the-surface to bef-sprayedLand moving molten paramn particles toward and into whereby saidparticles are heated during such movement.

12. In a spraying device of the character de- `"scribed, the combinationof: a head structure having an opening therein; means-for delivering astream of low pressure non-combustible gas to said opening; means insaid opening for dividing said stream of gas into inner and'outersubstantially concentric streams, said means including a tube disposedin said opening, said tubev having 1 an annular edge adapted to piercesaid stream.l whereby said inner stream may ow through said tube andsaid outer stream may ow through the space between said tube and thewalls Qi said opening; passage means communicating with the interior ofsaid tube; and meansfor delivering to said passagemeans, and thus tosaid inner stream of gasvmoving through said tube, the material to besprayed, whereby said material may be picked up by said gas constitutingsaid inner stream and discharged inside said outer stream of gas andagainst a surface to be coated, the 10W 15. A combination as deined inclaim 12, cluding means for heating the stream of gas before it reachesthe annular ledge of the tube, and in which the pressure of said streamof gas is not in excess of twelve inches of water.

16. A combination as defined in claim 12, in which the tube is a Venturitube.

17. A combination as deiined in claim 12, in which the means fordelivering the stream of low pressure gas to the opening includes ablower.

1 8. In a spraying device of the character de- I scribed, thecombination of: ahead structure providing an opening' therein; a tubedisposed in said opening and bounding an inner orlce means, said tubebeing smaller than said opening in said head structure to provide anannular orice means surrounding said inner orifice means; a tubularmember extending from said head structure in axial alignment with saidopeningoi said structure; means for owing a stream oi.' gas through saidItubular member, a portion of said stream of gas sowing through saidtube and another portion of said stream of gas owing around said tubeand through said annular oriiice means; heating means adjacent ,saidtubular member for heating saidgas beiore'it enters said tubularmember;l and means delivering the material to be sprayed to said tube,whereby said material Ais picked up bysaid stream of heated gas movingthrough said tube and is discharged from said inner oriiice means, .theheated gas flowing through rsaid annular oriilce means being dischargedin enveloping relationship with said material.'

19. In a spraying device ofthe class described, the combination of: .abody structure providing a chamber; a tubular member attached to saidbody structure and extending within said chamber; an annular heatingunit around and spaced from. said tubular member; means for iiowing astream of gas between said heating unit -and said` tubular member andthence into said tubular member; an atomizingimeans associated with saidbody structure and receiving at leastra portion of said heated gas;, andmeans for delivering thematerial to be sprayed to said atomizing means.

20. A combination as deiined in claim 19, in-

cluding a heat responsive means in the path of ilow of said hot gas asit moves trom the space .between said heating unit and said tubularmember and into said tubular member.

2l. `In a device for spraying material upon a surface, the combinationof: an outer venturi providing a throat and a flaredl portion extendingfrom said throat toward the surface to be sprayed; an'in'ner Venturitube providing a throat and bounding an inner orifice means at one end,said outer'venturi opening-directly to the atmosphere and said innerVenturi tube being within the outer venturi, said inner orifice meansbeing disposed adjacent the throat of said outer venturi,

` said inner Venturi tube being smaller than said outer venturi andcooperating therewith in forniing an annular orifice means; means foryiiowing gas through and from said inner and said annular orifice meansto form concentric streams moving through the atmosphere to the surface-to be sprayed; and means for introducing the material to be sprayedinto said throat of said of gas discharged from said annular orificemeans.

LUDWIG STOESLING.

